High-stability optical microscope

ABSTRACT

This invention provides a highly stable optical microscope that prevents drift and makes it possible to record images or take measurements for several hours with accuracy in the order of nanometers. The highly stable optical microscope of this invention includes the support structure ( 41 ) that accommodates and supports components including the optical imaging system, straight tube ( 28 ) that accommodates and supports components including the optical photometric system, and support structure ( 7 ) that accommodates and supports components including the illumination system. These support structures have a hollow pyramid or conical shape with a low center of gravity. The highly stable optical microscope of this invention features the objective lenses, imaging lenses, optical imaging and photometric systems that are mounted, forming a straight line, on the supporting structures that are symmetrical about the optical axis in both shape and mass.

TECHNICAL FIELD

This invention relates to image recording and measuring for an extendedtime using optical equipment, optical measuring instruments or opticalmicroscopes. When an optical microscope, in particular, is used torecord images or measurements for an extended time, the microscope isdisplaced minutely such that the object point (object) is shifted ordefocused (so-called drift). This invention provides a structure for ahighly stable optical microscope that is suitable for stable imagerecording or measuring for several hours with an accuracy in the orderof nanometers by preventing drift.

BACKGROUND OF THE INVENTION

Conventional optical microscopes may be compared to a willow tree. Thesample positioning stage, illumination system, optical observationsystem and other components mounted on the main stand (corresponding tothe trunk of the tree) lack balance and are asymmetrical about theoptical axis in both mass and shape. Such an unstable structure is shownin FIG. 1. In FIG. 1, 101 is a television camera, 102 is a relay lens,103 is a connecting tube, 104 denotes a straight tube, 105 denotes aneyepiece, 106 denotes a binocular tube, 107 denotes a lens mount, 108denotes a light source for fluorescence excitation, 109 denotes anincident-light fluorescence equipment, 110 denotes an arm, 111 denotes arevolver, 112 denotes an objective lens, 113 denotes a stage, 114denotes a vertical adjustment mechanism, 115 denotes a condenser, 116denotes a main stand, and 117 denotes a base and illumination system.

A conventional optical microscope as shown in FIG. 1 comprises a baseand a illumination system at the bottom, with one end installed on themain stand. An arm is supported on the side of the upper end of the mainstand, basically forming a U-shaped structure. The main stand supportsthe vertical adjustment mechanism for the sample mounting stage. Acondenser is set under the stage to guide illumination light from theillumination system to the sample being observed. The objective lenswith a revolver to choose the lens magnification is mounted under thearm. The incident-light fluorescence equipment, lens mount, straighttube, relay lens, and TV camera are installed above the arm. The lightsource for fluorescence excitation is attached to the side of theincident-light fluorescence device. The binocular tube and eyepiece aremounted on the side of the lens mount. In addition, the accessorymeasuring units, cameras, and other devices are mounted like “branchesand leaves” on a tree. The important components of an opticalphotometric system and optical imaging system, corresponding to thetrunk of the tree, are unstable because the main stand is set on one endof the base and the illumination system. This cantilever structure makesnot only the “branches and leaves” but also the thin “trunks” to swaylike a willow tree.

In the conventional optical microscope, a half-mirror (includingdichroic mirror) is typically installed on the inlet of the illuminationsystem (incident-light fluorescence, total internal reflectionfluorescence, transmitted light fluorescence, incident polarized light,transmitted polarized light, bright field incidence, optical tweezers,and etc.) and also on the inlet of the optical monitor system. A singleimaging lens is, however, commonly used to reduce cost. The supportfixtures for the illumination system are integrated with the opticalimaging and photometric systems, with the result that instability causedby asymmetry in the shape and mass of the support fixtures for theillumination and monitor systems and shrinkage/elongation of thosesupport fixtures due to temperature dependency bring about thefluctuation of the optical axis in the optical imaging and photometricsystems.

A new field of study called single-molecule physiology is becomingpopular. In this science, the motion of protein and other biologicalmolecules is observed and controlled. Optical microscopes are essentialtools in this study and they require accuracy of several nanometers foreffective analysis because the motions of the biological substances areminute.

Currently available optical microscopes are not stable enough and driftoccurs during observation, recording and measurement performed forextended times. The observation results are always subject to errors.

The present invention offers a highly stable optical microscope that isfree from defocusing of samples and displacement (drift) of the objectpoint (object) during observation. A dedicated, rather than common,imaging lens is mounted for each optical system headed by an imaginglens.

By installing a dedicated imaging lens for each system, for example thetelevision camera system, the center of the imaging lens and focalposition are displaced together. This principle is described belowreferring to FIGS. 2A and 2B.

Assume displacement in the X-Y direction occurs as shown in FIG. 2Brelative to the ideal position shown in FIG. 2A due to the effects ofinstability caused by asymmetry in the shape and mass of the supportfixtures. Since the imaging lens and television camera are integrated,the object is successfully imaged without relative displacement of thecenter of the imaging lens and the focal position, although light fluxis somewhat deviated.

This is an application of the principle of astronomical telescopes.There is no displacement, parallel or perpendicular to the optical axis,of the image of the object relative to the imaging lens, provided thatthe telescope only translates without inclination.

DISCLOSURE OF THE INVENTION

The technical means adopted by this invention is a structure of a highlystable optical microscope in which the objective lens, imaging lens,optical imaging system and optical photometric system are mountedwithout deviation, and while forming a straight line, on the straightguide mechanism and support structures that are symmetrical about theoptical axis in both shape and mass.

Another technical means adopted by this invention is a structure of ahighly stable optical microscope in which the support structure for theoptical imaging system and photometric system are either a squaretruncated pyramid or circular truncated cone, to prevent changes ininclination caused by temperature fluctuations, vibration or otherfactors.

Another technical means adopted by this invention is a structure of ahighly stable optical microscope in which, in an infinity correctedoptical microscope, a half mirror (including dichroic mirror) and animaging lens are combined and mounted at, the inlet of the opticallighting system (incident-light fluorescence, total internal reflectionfluorescence, transmitted light fluorescence, incident polarized light,transmitted polarized light, bright field incidence, optical tweezersand etc.) and also the optical monitor system, respectively, to make theoptical imaging and photometric systems stable and free from theasymmetry of shape and mass and instability caused by temperaturedependency of the metal support structures by utilizing the principle ofa telescope.

Another technical means adopted by this invention is a structure of ahighly stable optical microscope in which the sample base, symmetricallybuilt in shape and mass about the optical axis, and the objective lens(sample section) are integrated and supported by the support structurethat is independent of all imaging lenses, and integrated into thesystem at a low center of gravity.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a typical conventional optical microscope.

FIGS. 2A and 2B show the principle that the center of an imaging lensand the focal position are displaced by integrating the imaging lenswith, for example, a TV camera.

FIG. 2A shows the ideal position (movement-free).

FIG. 2B shows that the entire optical imaging system has moved in theX-Y direction.

FIG. 3 shows an optical microscope structured as this invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The highly stable optical microscope of this invention is describedbelow referring to FIG. 3.

The infinity corrected optical microscope comprises an optical imagingsystem (consisting of photometric iris 17, relay lens support fixture18, relay lens 19, television camera support fixture 20, and televisioncamera 21), an optical photometric system (consisting of straight tube28, photometric iris 29, relay lens fixture 30, relay lens 31,photometric system support fixture 32, and photometric system 33), anillumination system (consisting of incident-light fluorescence 12,total-internal- reflection-fluorescence, transmitted light fluorescence,incident polarized light, transmitted polarized light, bright fieldincidence, optical tweezers 10 and 11, and etc.), and the infinitycorrected objective lens 2 and imaging lens 16 built into the opticallighting system. A hollow conical support base 7 is fixed on thevibration isolating table 15, which is supported by support legs 38. Theoptical tweezers port 10, incident-light fluorescence equipment 12, anda first optical monitor system 13 are installed on the expanded sectionbelow said support base 7, facing toward the center.

The optical tweezers illumination system 11, mounted on the vibrationisolating table 15, is connected to the optical tweezers port 10. Thebase 14, with imaging lens 16 at the center, is installed at the lowerpart of the hollow section of said support base 7. The flat part 39 ofsaid base 14 rests on the vibration isolating table 15 while its leg 40is inserted into the center of the vibration isolating table 7. Supportstands 9 are set on said base 14, supporting a substrate 8 at the top. Amounting base 6, Y-axis coarse transfer base 5, X-axis coarse transferbase 4, and X-, Y-, Z-axis finely adjustable sample base 3 are installedon said substrate in this order. The sample 1 to be observed is placedon said X-, Y-, Z-axis finely adjustable sample base, and is illuminatedby said lighting system.

The transmitted light illumination system 23, dark field illuminator 26,and a second optical monitor system 27 are mounted on the narrowersection at the upper part of the support base 7, facing toward thecenter. The condenser lens 22 is mounted on the tip of the condenserlens support fixture 24, which is fixed on the support base 7. Theimaging lens 25 for the lighting system is mounted on the flat part ofthe tip of the support base 7 at the center.

The hollow and trapezoidal straight tube 28, fixed on the flat part atthe tip of said support base 7, holds as installed, the photometric iris29, relay lens support fixture 30, relay lens 31, photometric systemsupport fixture 32, and photometric system 33 in this order, generatingthe primary 36 and the secondary 37 image on the photometric side.

A hollow and inverted trapezoidal support structure 41 mounted on thebottom face of the vibration isolating table 15. The hollow section ofthe support structure 41 accommodates, as installed, the photometriciris 17, relay lens support fixture 18, relay lens 19, television camerasupport fixture 20, and television camera 21 in this order, generatingthe primary 34 and the secondary 35 image on the imaging side.

As described above, the highly stable optical microscope of thisinvention features a construction in which the infinity correctedobjective lens 2, imaging lens 16, imaging lens 25 for the lightingsystem, optical imaging system (consisting of the photometric iris 17,relay lens support fixture 18, relay lens 19, television camera supportfixture 20, and television camera 21), and the optical photometricsystem (consisting of the straight tube 28, photometric iris 29, relaylens fixture 30, relay lens fixture 31, photometric system supportfixture 32, and photometric system 33) are mounted without deviation,while forming a straight line, on the straight guide mechanism that issymmetrical about the optical axis in both shape and mass.

The infinity corrected system is integrated into the mechanism of thisinvention, and the optical imaging and photometric systems each have anintegrated imaging lens. This allows utilization of the merit of atelescope in that translation does not lead to defocusing or movement(drift) of the object point (object) during observation for extendedtimes as long as inclination does not change. A typical example of thisstraight guide mechanism comprises a cylinder and a column. Thecylindrical section is movable in the direction of the optical axis.

The sample is focused on the sample base 3 which features finelyadjustable X, Y, and Z axes. The adjustable sample base 3 is symmetricalabout the optical axis and incorporates a capacitance type sensor tofeed back displacement to the piezo drive mechanism to maintain thefocal position.

A half mirror 51 (including dichroic mirror) and an imaging lens 52 areset on the inlet of the optical lighting system (incident-lightfluorescence 12 total internal reflection fluorescence, transmittedlight fluorescence, incident polarized light transmitted polarizedlight, bright field incidence, optical tweezers port, 10 and 11, etc.).The illumination system is supported by a separate support fixtureindependent of the optical imaging and photometric systems to assurethat instability due to asymmetry of the shape and mass will not affectthe optical imaging and photometric systems.

Even if the optical imaging, photometric or illumination systems shouldmove, the above principle of a telescope works and, moreover, a changein inclination is prevented by mounting on the solid trapezoidal(pyramid-type) support base 7. Heavy and large-sized components such asan optical tweezers illumination system are further separated anddirectly mounted on the vibration isolating table 15, preventingunstable factors such as overlapped imbalance and inclination.

Therefore, if the illumination system should be displaced due toexternal vibration or other causes, the sample and the objective lensare not affected by the displacement.

The single most important factor of instability is the relative motionof the sample and objective lens.

For this reason, the sample 1, infinity corrected objective lens 2, X-,Y-, Z-axes finely adjustable sample base 3, X-axis coarse transfer base4, Y-axis coarse transfer base 5, and mounting base 6 are respectivelyfixed and integrated such as by vacuum suction.

This integration to eliminate the relative motion of sample andobjective lens is very effective for maintaining stability. These partsare furthermore directly mounted on the vibration isolating table 15 andarranged at a low center of gravity to make the solution more effective.

(The conventional system, like a willow tree with thin trunks swaying inthe wind, is replaced by a separately structured system comprising aconstruction like Tokyo Tower with a building directly below the Tower.The integrated sample and objective lens correspond to the building andare located with a low center of gravity.)

This invention may be implemented in various other forms of embodimentwithout deviating from the spirit of the main features. Theabove-mentioned embodiments are therefore only a few examples and shouldnot be construed as limiting.

INDUSTRIAL APPLICABILITY

The highly stable optical microscope of this invention features anobjective lens, imaging lens, optical imaging and photometric systemsthat are mounted without deviation, while forming a straight line, onthe straight guide mechanism and support structures that are symmetricalabout the optical axis in both shape and mass as described above. Thehighly stable optical microscope of this invention makes it possible tomeasure the position of molecules and molecular movement in the order ofnanometers in molecular biology and biophysics. It is also possible torecord images for an extended time without drift In the infinitycorrected optical microscope, a half mirror (including dichroic mirror)and an imaging lens are combined and mounted at the inlet of theillumination system (incident-light fluorescence, total internalreflection fluorescence, transmitted light fluorescence, incidentpolarized light, transmitted polarized light, bright field incidence,optical tweezers and etc.) and the optical monitor system. This providesfreedom for the mounting positions and compatibility of the respectivecomponents, enabling an optical microscope system that is expandable andhighly stable.

1. A highly stable optical microscope, wherein an objective lens, animaging lens, an optical imaging and a photometric system are mountedwithout deviation, forming one single straight line, on a straight guidemechanism and a hollow support structure, surrounding the straight guidemechanism, that are symmetrical about an optical axis in both shape andmass; and the support structure for the optical imaging and photometricsystem is a square truncated pyramid or a circular truncated cone toprevent changes in inclination due to temperature fluctuations andvibration.
 2. The highly stable optical microscope as claimed in claim1, wherein a sample base and the objective lens, arranged symmetricallyin shape and mass about the optical axis, are integrated and supportedby support structures that are independent of all imaging lenses and areintegrated at a low center of gravity close to a vibration isolatingtable.
 3. The highly stable optical microscope as claimed in claim 1,wherein in an infinity corrected optical microscope, a half mirror andthe imaging lens are combined and mounted at the inlet of an opticalillumination system and an optical monitor system respectively, andwherein the optical illumination system is a combination of at least anincident-light fluorescence, a total internal reflection fluorescence, atransmitted light fluorescence, an incident polarized light, atransmitted polarized light, a bright field incidence, and an opticaltweezer.
 4. The highly stable optical microscope as claimed in claim 3,wherein a sample base and the objective lens, arranged symmetrically inshape and mass about the optical axis, are integrated and supported bysupport structure that is independent of all imaging lenses and isintegrated at a low center of gravity close to a vibration isolatingtable.
 5. The highly stable optical microscope as claimed in claim 3,wherein the half mirror is a dichroic mirror.
 6. A highly stable opticalmicroscope, wherein an objective lens, an imaging lens, an opticalimaging and a photometric system are mounted without deviation, whileforming a straight line, on a straight guide mechanism and a hollowsupport structure that are symmetrical about an optical axis in bothshape and mass, wherein a sample base and the objective lens, arrangedsymmetrically in shape and mass about the optical axis, are integratedand supported by support structures that are independent of all imaginglenses and are integrated at a low center of gravity close to avibration isolating table; wherein a half mirror and the imaging lensare combined and mounted at the inlet of an optical illumination systemand an optical monitor system respectively, the half mirror beingdichroic mirror; and wherein the optical illumination system is acombination of at least an incident-light fluorescence, a total internalreflection fluorescence, a transmitted light fluorescence, an incidentpolarized light, a transmitted polarized light, a bright fieldincidence, and an optical tweezer.